Scroll wheels have been provided on computer mice and used by computer operators to move an image relative to a display screen of a host computer. A scroll wheel assembly includes a rotatable scroll wheel and a sensor that are typically included in a housing for a peripheral computer device such as a mouse. Typically, a portion of the scroll wheel protrudes upwardly out of an opening in its housing and is rotated in order to vertically scroll the image along the screen. An example of a mouse including a known scroll wheel assembly is described in U.S. Pat. No. 5,912,661, entitled “Z-ENCODER MECHANISM” which is hereby fully incorporated by reference.
Scrolling, as used herein, describes the movement of an image relative to a display screen in a particular direction as such term is commonly used in the art. For example, the term “scroll down” as used herein relates to moving the viewable contents of a file (such as a text document or image) relative to display screen by an amount to produce an effect of moving down in the document or image. Similarly, the terms scroll up, scroll left and scroll right relate to moving the viewable contents of a file relative to a screen by an amount to produce an effect of moving in the document or image up, left, and right, respectively. The term scrolling as used herein also includes panning, which is the automatic scrolling of an image.
In operation, a conventional scroll wheel is normally rotated about a transversely extending axis secured within a housing. An encoder wheel is coupled to the scroll wheel and rotates when the scroll wheel rotates. As the scroll wheel is rotated, an encoder senses the rotation of the encoder wheel, and delivers a corresponding signal to a host computer. That signal can be used to move an image, as is known in the art and disclosed in U.S. Pat. No. 5,912,661. Notably, this allows a user to scroll the image without changing the position of the mouse and/or the cursor, and instead only requires rotating the scroll wheel (versus the entire mouse or other device) with a thumb or finger. However, displayable portions of spreadsheets and many other types of documents and screen images are often wider than the display screen, and the user must also scroll horizontally across the screen to see the entire file. When the user needs to move the image horizontally across the display screen, the user must typically perform additional steps beyond what is required for vertical scrolling. This can include locating a graphical user interface in the form of a horizontal scroll bar (usually located near the bottom of the display), positioning the cursor on the scroll bar, and then rotating the wheel. Locating the scroll bar can be very difficult for people with bad eyesight, small display screens and/or poor hand-eye coordination. Using a horizontal scroll bar also requires a user to shift his or her gaze from the portion of the document being viewed, and then relocate that portion after horizontal scrolling. Even if the size of the horizonatl scroll bar and/or the screen resolution can be adjusted, the user must nevertheless perform additional pointing tasks which are more time-consuming and mentally intensive than simply rotating a wheel or pushing a button. Alternative graphically assisted tools for horizontal scrolling (e.g., positioning a cursor over a horizontal scroll bar, selecting the scroll bar, and moving the cursor) also require cursor repositioning, and have similar drawbacks.
If the user does not accurately position the cursor over the horizontal scroll bar, the image will not scroll horizontally with respect to the display screen as he or she operates the mouse cursor of the graphical interface or rotates the mouse wheel. Instead, when using the mouse cursor on the graphical interface, nothing happens until he or she tries again to position the mouse cursor correctly on the scroll bar's points of operation. Or, when using the mouse wheel, the image will move vertically relative to the display screen and erroneously change the displayed image. These errors will force the user to take additional steps to reposition the desired image on the display screen. These steps include the user confirming that the cursor is not positioned on the horizontal scroll bar and rotating the scroll wheel in the opposite direction to return the image to its previous position. Unfortunately, repositioning an image can lead to errors if the image is being amended. For example, the user may not return the image to its previous position. As a result, he may amend the wrong section of the image. Even if the proper image or portion of an image is returned to the display screen, the user must still attempt to locate the bottom, horizontal scroll bar a second time in order to finally move the image in a horizontal direction.
Microside Corporation of Miami, Florida, offers a “Micro Scroll II” mouse that permits a user to scroll an image in multiple perpendicular directions. This mouse includes a first rotatable wheel for scrolling an image up and down, and a second, separate rotatable wheel for scrolling an image left and right. The rotatable wheels are oriented so they extend and rotate in planes that are perpendicular to each other. The two scroll wheels are independently operable. However, this arrangement has drawbacks. The two wheels take up limited space on the upper surface area on the mouse, which could be used for supporting the hand of the user or for additional input keys. Further, the two wheels are relatively small in size so as to accommodate both wheels on the upper surface of the mouse. The smaller sized scroll wheels make the scrolling more difficult to control. Additionally, the location of the horizontal scroll wheel can be inconvenient for effective control. Further, with this design, it might be difficult for some users to easily reach and manipulate both of the wheels.
Accordingly, there remains a need for improved input devices facilitating scrolling in multiple directions.